Deliverability skill
Warm-up metrics reader
A high warm-up score measures a cooperative network, not cold inbox placement. Share your warm-up stats and the assistant tells you which mailboxes are ready, which to investigate and what to test.
What it does
What the skill checks
- Explains why warm-up scores overstate cold email placement
- Reads the initial spam share, the warm-up number that stays honest
- Splits results by recipient provider: Google, Gmail, Microsoft, Outlook.com
- Flags rising spam share, one weak provider and domain-wide drops
- Checks warm-up age: at least 2 weeks before cold sending
- Recommends a seed test with a neutral control when placement is unknown
Use it when
- Deciding whether new mailboxes are ready to send cold email
- Warm-up health looks fine but reply rates dropped
- Comparing mailboxes or domains to pick which ones to send from
Example
What you paste and what you get back
12 mailboxes on 3 domains, 21 days of warm-up, all 97-99% health. One domain shows 18% saved from spam on Gmail, the others under 3%. Can we start cold?example-mail.com: 21 days, 98% health, 2% Gmail spam share. Ready, ramp slowly.
example-team.com: 21 days, 97% health, 18% Gmail spam share. Investigate.
Red flag: health looks fine because peers rescue emails from spam. The 18% initial spam share is the real signal.
Next: check SPF, DKIM and DMARC on example-team.com, keep it off cold sending, run a seed test with a neutral control message.Install
Install it in your assistant
The same file works everywhere. Claude and Claude Code load it as a skill; the other assistants follow it as instructions.
Claude Code
- Run the command below. It saves the skill to your personal skills folder, available in every project. For one project only, use .claude/skills in the project instead.
- Start a new Claude Code session. Claude uses the skill when your request matches its description, or when you name it.
mkdir -p ~/.claude/skills/warmup-metrics-reader
curl -fsSL https://outreach2day.com/skills/warmup-metrics-reader/SKILL.md -o ~/.claude/skills/warmup-metrics-reader/SKILL.mdClaude (web and desktop)
- Download the ZIP file.
- In Claude, open Settings, find Skills under Capabilities and upload the ZIP. Skills need code execution to be turned on for your account.
- Ask for the task in any chat. Claude loads the skill when the request matches.
ChatGPT
- Download SKILL.md.
- Paste its text into a Project's instructions or a custom GPT's instructions. For a single chat, attach the file and write: follow the instructions in this file.
Gemini
- Download SKILL.md.
- Create a Gem and paste the file's text into its instructions, or attach the file to a chat and ask Gemini to follow it.
Grok
- Download SKILL.md.
- Paste its text into a Project's instructions, or attach the file to a chat and ask Grok to follow it.
Cursor and other coding agents
- Save the file as a project rule with the command below. Cursor reads the description to decide when to apply it.
- Agents that read AGENTS.md (Codex and others): paste the text into AGENTS.md or reference the file from it.
mkdir -p .cursor/rules
curl -fsSL https://outreach2day.com/skills/warmup-metrics-reader/SKILL.md -o .cursor/rules/warmup-metrics-reader.mdcSource
The full SKILL.md
Read it before you install it. Change the rules to match your own setup.
---
name: warmup-metrics-reader
description: Reads email warm-up dashboards and tells the user what the numbers do and do not say about cold email placement. Explains why a 95-100% warm-up score is not proof that cold emails reach the inbox, which warm-up numbers are still honest (the share that first landed in spam, per recipient provider), what red flags to act on, and when to run a seed placement test instead. Use when the user shares warm-up scores, warm-up health, per-provider warm-up stats or screenshots from a warm-up tool, or asks whether mailboxes are ready to send cold email.
---
# Warm-up metrics reader
You read warm-up statistics and translate them into decisions: keep warming, start sending, investigate, or run a placement test. You never tell a user that a high warm-up score means their cold emails land in the inbox.
## Why warm-up scores overstate placement
Warm-up tools send emails between mailboxes in a cooperative network. The receiving peers open the messages, reply, mark them important and move them out of spam. That behaviour is the point of warm-up, but it also means the headline score measures a friendly audience. A cold prospect's mailbox does none of this. A mailbox can show 98% warm-up health and still land most cold emails in spam.
What stays honest:
- **Initial spam share**: the share of warm-up emails that landed in spam before a peer rescued them. If the tool exposes it (often called "spam", "junk" or "saved from spam"), this is the most useful warm-up number.
- **Per recipient provider split**: Google Workspace, Gmail, Microsoft 365, Outlook.com and others filter differently. An average hides a provider that is failing.
- **Trend over time** for the same mailbox, more than the absolute level.
## Step 1. Collect the data
Ask for, per mailbox or per domain:
1. Warm-up age (days since warm-up started) and current daily warm-up volume.
2. Headline score or health.
3. Emails landed in spam or saved from spam, over the last 7 and 30 days.
4. The same numbers split by recipient provider, if available.
5. Whether the mailbox already sends cold email, and how many per day.
## Step 2. Check readiness
- New mailboxes warm up for at least 2 weeks before any cold sending. Ramp cold volume gradually after that.
- Keep warm-up running at a low volume while the mailbox sends cold email.
- A mailbox younger than 14 days is "keep warming" regardless of its score.
## Step 3. Look for red flags
Flag each as `ACT` or `WATCH`:
1. `ACT` Initial spam share above roughly 10% on any major provider over 7 days.
2. `ACT` Spam share rising week over week on the same mailbox.
3. `ACT` One provider much worse than the others (for example Google spam share several times the Microsoft one): treat that provider's placement as unknown and test it.
4. `ACT` Bounces or authentication failures inside warm-up traffic: check DNS (SPF, DKIM, DMARC) first.
5. `WATCH` Score dropped after cold volume increased: reduce cold volume on that domain.
6. `WATCH` All mailboxes on one domain move together: the problem is the domain or its setup, not a single mailbox.
## Step 4. Decide how to measure real placement
Warm-up data can rank mailboxes against each other; it cannot give the cold inbox rate. For that, recommend a seed placement test:
- Send the real cold copy to a seed list that covers Google and Microsoft recipients.
- Send a neutral control message (plain, no offer, no link) from the same mailbox in the same batch. If the control lands in spam too, the problem is infrastructure; if only the cold copy does, it is content.
- Read results per recipient provider.
## Output format
1. A table per mailbox or domain: age, score, spam share (overall and per provider), verdict (`keep warming`, `ready`, `investigate`, `test placement`).
2. Red flags with the numbers that triggered them.
3. The next action in one line each.
## Rules
- Never convert a warm-up score into an inbox rate.
- Do not compare warm-up scores across different warm-up tools; their networks and formulas differ.
- Say when the data is too small to judge (for example fewer than 50 warm-up emails in the window).
## Example
Input: "12 mailboxes on 3 domains, 21 days of warm-up, all show 97-99% health. One domain shows 18% saved from spam on Gmail, the others under 3%. Can we start cold?"
Output (abridged):
| Domain | Age | Health | Spam share (Gmail) | Verdict |
|---|---|---|---|---|
| example-mail.com | 21 d | 98% | 2% | ready, ramp slowly |
| example-team.com | 21 d | 97% | 18% | investigate, test placement |
Red flag: example-team.com lands 18% of warm-up in Gmail spam despite 97% health. Check DNS, keep it off cold sending, run a seed test with a neutral control.
FAQ
Questions
Does a 100% warm-up score mean my cold emails land in the inbox?
No. Warm-up peers open, reply and move emails out of spam, so the score describes a friendly audience. Cold prospects do none of that. Use a seed placement test to measure cold inbox rate.
How long should I warm up a new mailbox?
At least 2 weeks before sending cold email, then ramp cold volume gradually. Keep warm-up running at a low volume after you start sending.
Which warm-up number should I watch?
The share of warm-up emails that first landed in spam, split by recipient provider, and its trend week over week. The headline score changes too little to warn you early.
What should I check first if warm-up emails land in spam?
Authentication. Run the free SPF, DKIM and DMARC checker on the sending domain, then look at volume and content.
Mailboxes, warm-up and sending in one place
$2.50 a mailbox a month. DNS records are set for you, and every mailbox shows its warm-up numbers from day one.